With his controversial victory over Paul Daley, Koscheck earned the right to coach against on the twelth season of TUF and then fight Georges St. Pierre for the welterweight title. St. Pierre defeated Koscheck via unanimous decision. During the fight, the champion continually landed jabs and broke Koscheck's right orbital bone in the first round.
After recovering, Koscheck stated in July 2011 that he wanted his first fight back to be at middleweight. Possible opponents varied from former TUF rival Chris Leben and undefeated wrestling prospect Chris Weidman.
Instead, Koscheck next stepped in at welterweight to replace an injured Diego Sanchez against former welterweight champion and Hall of Famer Matt Hughes. He knocked Hughes out with one second left in the first round.
Koscheck next called out former WEC welterweight champion and UFC welterweight contender Carlos Condit and Condit accepted the challenge. Condit next stepped in to replace undisputed champion Georges St. Pierre against former Strikeforce welterweight champion Nick Diaz for the UFC interim welterweight title. Mike Pierce stepped up to face Koscheck. Koscheck defeated Pierce via a close and controversial split decision.
Koscheck wasted no time addressing any possible controversy, next signing to face fellow contender Johny Hendricks in what could be considered a UFC welterweight title eliminator bout. Hendricks defeated Koscheck via a close and controversial split decision, reinjuring Koscheck's eye in the process.
Koscheck was next rumored to face returning former Strikeforce welterweight champion Nick Diaz in February 2013. Instead the opponent for February was announced to be returning Strikeforce veteran Robbie Lawler. Lawler scored a slightly controversial first round technical knockout over Koscheck for his second straight loss.
Koscheck inexplicably next signed to face top contender and jiu jitsu ace Demian Maia. Koscheck was unfortunately soon enough injured.
After recovering Koscheck signed to fight Strikeforce veteran Tyron Woodley. After a back and forth fight Woodley knocked out Koscheck with a thunderous pair of right hands. Koscheck bitterly contemplated retirement afterwards and didn't fight for over a year.
In late November 2014 a little over a year after the Woodley fight Koscheck signed to return to fight rising contender Neil Magny. The fight never materialized. Koscheck soon returned to sign and fight fellow veteran Jake Ellenberger for February 2015.
Koscheck showed some pep against Ellenberger but also significant and unsurprising ring rust losing via a brutal third round guillotine choke submission. There was some speculation of Koscheck retiring.
Instead about a week after the fight, Koscheck stepped in to replace Ben Saunders against striker Erick Silva in Brazil on three weeks' notice. Koscheck gave it all he had coming after Silva looking for a finish but Silva finished Koscheck via guillotine choke submission towards the end of the first round.
Koscheck's UFC contract ran out with that final fight and the UFC opted not to re-sign him.
Koscheck signed with the UFC's biggest rival promotion Bellator in late June 2015, immediately calling out old enemy Paul Daley.
- Josh Koscheck vs. Pete Spratt
- Drew Fickett vs. Josh Koscheck - The fight was Koscheck's first loss.
- Josh Koscheck vs. Ansar Chalangov
- Josh Koscheck vs. Jonathan Goulet
- Josh Koscheck vs. Jeff Joslin - The bout was Jeff Joslin's UFC debut and his last fight since the end of 2006.
- Josh Koscheck vs. Diego Sanchez - The fight was Diego Sanchez's first loss. He blamed the loss on a staph infection.
- Georges St. Pierre vs. Josh Koscheck 1 - Both fighters were nearly identical, the same exact height and reach with Koscheck being three years older. The fight was Georges St. Pierre's first after losing the title in an upset to Matt Serra. The fight was also only Koscheck's second professional mixed martial arts loss. The fight was considered by some to be one of the most competitive in St. Pierre's career, excepting the first fight with Matt Hughes.
- Josh Koscheck vs. Dustin Hazelett
- Josh Koscheck vs. Chris Lytle - The fight was considered to be one of the bloodiest fights in UFC history.
- Josh Koscheck vs. Yoshiyuki Yoshida - The fight was ended with a brutal highlight reel knockout victory for Koscheck.
- Josh Koscheck vs. Paulo Thiago - The fight was then-undefeated Paulo Thiago's UFC debut.
- Josh Koscheck vs. Frank Trigg - The fight was Frank Trigg's return to the UFC.
- Josh Koscheck vs. Paul Daley - The fight was both for the number one contendership in the UFC welterweight division but it was for the chance to coach the twelth season of TUF against Georges St. Pierre. Paul Daley was cut after the fight for a highly illegal and unsportsmanlike sucker punch he landed after the fight ended to Koscheck.
- Georges St. Pierre vs. Josh Koscheck 2 - The fight was for the welterweight title with Georges St. Pierre defending. Koscheck suffered a broken right orbital bone in the first round.
- Josh Koscheck vs. Matt Hughes - Koscheck came in on just over two weeks' notice, replacing an injured Diego Sanchez.
- Josh Koscheck vs. Mike Pierce
- Robbie Lawler vs. Josh Koscheck - The fight was Robbie Lawler's return to the UFC and his return to the welterweight division.
- Erick Silva vs. Josh Koscheck